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Renesas Electronics America Inc.© 2012 Renesas Electronics America Inc. All rights reserved.
Driving E Ink Displays
© 2012 Renesas Electronics America Inc. All rights reserved.2
Renesas Technology & Solution Portfolio
© 2012 Renesas Electronics America Inc. All rights reserved.3
Agenda
E Ink Background and Overview Display Options Comparison to LCD Display Construction Technical Stuff
Display Structure How does it switch Display terms Driving and Electronics Integration Standard Reliability testing
Contact Addendum – Display concepts
© 2012 Renesas Electronics America Inc. All rights reserved.4
E Ink at a Glance
M SManufacturing and Supply Chain Center Sales and FAE Center
VR Research and Development Center Vertical Integration Site
M RS
M RS
M RV
TaipeiHsinchuTaiwan
Yangzhou, China
Icheon, South Korea
SShenzhen, China
Santa Ana, USA
Bay Area, USAShanghai, China
Tokyo, JapanSchwalbach, Germany
R
SS
SV
Cambridge, USA
S
S
E Ink Corporation spun out of MIT Media Lab in 1997 E Ink Holdings formed by 2009 combination of E Ink
Corporation and PVI
© 2012 Renesas Electronics America Inc. All rights reserved.5
Market Overview
Active Matrix Business Unit Triton and Pearl
Segmented Business Unit SURF Segmented Displays High Channel Segmented Displays (Q4 12’)
Ink in Motion Point of Purchase
© 2012 Renesas Electronics America Inc. All rights reserved.6
Display Options
Active Matrix
SURFSegmented
High Channel Segmented
Backplane Glass Polymer Glass
Shape Square/rectangular Any 2D Shape99% Custom
Square/rectangular
Minimum Size 4” 4mm^2 2.5”
Thickness 1.5mm 380 microns 1.5mm
Capacity 160 – 200 Dpi ~ 200 Segments Up to 600 segments
Cost $$$$$ $ Q4 2012
© 2012 Renesas Electronics America Inc. All rights reserved.7
SURF Display Options
Segmented Display Cell (SDC) Customer integrates the display with electronics
Segmented Display Module (SDM) Display driver is bonded to the SDC SDM is then connected to the MCU
© 2012 Renesas Electronics America Inc. All rights reserved.8
E Ink Segmented vs. TN-LCD
Feature TN-LCDInfinite viewing angleBi-StableShatterproofAny 2D shapeReflectiveBrighter White StateDarker Dark stateDaylight readable
© 2012 Renesas Electronics America Inc. All rights reserved.9
Display construction
Flexible backplane is made of either Polyimide or PET PET ~ carbon based (200 um design rules) Polyimide ~ copper or gold based (100 um design rules)
Displays across a broad range of sizes From 1 segment to 200+ segments Alpha-numeric, and iconic, virtually any shape
Almost unlimited design potential LCD is glass based Not limited to 90 degree angles
The opportunity to use displays where they have not previously existed
© 2012 Renesas Electronics America Inc. All rights reserved.10
Best Applications for E Ink
Power requirements have made a display unfeasible Novatel Wireless
Form factor limitations have made the incorporation of a display impractical Lexar
© 2012 Renesas Electronics America Inc. All rights reserved.11
Lets Get Technical
© 2012 Renesas Electronics America Inc. All rights reserved.12
Display Cell Structure
1.5 mm
- 2 mils UV/PET- 1 mil PSA adhesive- 2 milsACLAR- 2 mils EVA adhesive
FrontBarrier
BackElectrode
- PET / FR4 / Polyimide- pixel electrode layers(not shown)
Inactive area on backplane
Front Electrode- 188 um PET with conductiveITO coating.
- 25 um polyurethane
Microcapsule(~30 micron sphere)
Binder - thermoplastic polyurethane(note, this material also surroundsmicrocapsules)
Lamination Adhesive
BackBarrier
-2 mils EVA adhesive-1.25 mil PE-thin PE tie layer (not shown)- 0.3 mil AL foil- thin PE tie layer (not shown)- 0.5 mil PET
© 2012 Renesas Electronics America Inc. All rights reserved.13
How does it work?•Each area needing to be switched must have its own dedicated drive line.•To drive the display the top electrode and any bottom electrode or segment must be in opposite states.
•When charged the pigment moves up or down in the capsule.•If the charge does not change the pigment remains in place.
•A capsule can display a black and white state at the same time.
Capsules are 30-70um in diameter
© 2012 Renesas Electronics America Inc. All rights reserved.14
Display Terms
Segment – Any Character or characters which need to change state. Note: Multiple segments can be tied to the same line.
Background/Field – Essentially a segment, but is defined as the largest segment which is typically held in the opposite state to other segments.
Front/Top Electrode – Drive line connection to the top electrode layer. This creates the DC potential for any segment to switch.
© 2012 Renesas Electronics America Inc. All rights reserved.15
SURF Segmented Display Cell
MCU
Display Driver
1.8 - 3.3 VBat
•FPC Connector•ACF bonding•Hot bar bonding
SPI or I^2C
Interface options
© 2012 Renesas Electronics America Inc. All rights reserved.16
SURF Segmented Display Module
MCU
1.8 - 3.3 VBat
SPI or I^2C
15VDisplay Driver
•FPC Connector•ACF bonding•Hot bar bonding
Interface options
© 2012 Renesas Electronics America Inc. All rights reserved.17
Driving E Ink Displays
15 Volt 5 Volt
Fastest Update Time
240 milliseconds(Range 50-400ms @
25C)
720 milliseconds(Range 500 - 2000ms
@ 25C)Percent of availableContrast
100% 80 - 90%
Display Drivers
E Ink Specific displaydriver
MCU
Vendors Dialog Semiconductor
Renesas
PowerConsumption
.5ua cm^2 .5ua cm^2
© 2012 Renesas Electronics America Inc. All rights reserved.18
Waveforms
In it’s simplest form we drive the display with a square wave operating between 0 – 5V or 0 – 15V.
© 2012 Renesas Electronics America Inc. All rights reserved.19
Global Update
Global update - all segment switch during update Even if it reverts to its original state
Global Update provide a pleasant appearanceEven objects that do not change will flash Global update waveforms can switch from B->W or from W->B
In this transition all segments which are not black are driven black We then drive to white any segments not needed to complete the “5” Note: The background/field is switched in this update
© 2012 Renesas Electronics America Inc. All rights reserved.20
Global Update, cont
Image: Black to White update:
In this transition all segments which are not white are driven white We then drive to black any segments needed to complete the “5” Note: The background/field is switched in this update
© 2012 Renesas Electronics America Inc. All rights reserved.21
Local Update In this transition the segments needed to complete the “5” are driven black We then drive to white any segments not needed to complete the “5” Note: The background/field is not switched in this update
Image: White to Black update:
© 2012 Renesas Electronics America Inc. All rights reserved.22
Local Update Waveforms, cont
Image: Black to White update:
In this transition all the segments not needed to complete the “5” are driven white We then drive to black any segments needed to complete the “5” Note: The background/field is not switched in this update
© 2012 Renesas Electronics America Inc. All rights reserved.23
Key Driving Points
Do drive the ink to a saturated optical state Do drive the ink in a DC-balanced manner
Net impulse across ink should sum to zero At constant-voltage, this means equal pulses in opposite
directions.
Do Not overdrive the ink Do Not apply pulses longer than needed to reach
saturated optical states. Do Not re-drive ink in the same direction.
© 2012 Renesas Electronics America Inc. All rights reserved.24
Integration
Can E Ink displays be used with touch screens? Yes, E Ink displays have been used with
– Capacitive touch screens on top– Resistive touch screens– IR
Can alternative lighting be used? Yes
– Side lighting and front lighting are commonly used with our displays.
Can alignment features be added to the display? Yes
– Positioning features such as holes or notches are commonly added to assist in the positioning of displays in housings.
Is passive Matrix possible? No
© 2012 Renesas Electronics America Inc. All rights reserved.25
Standard Testing Environments
Name Test Items Test Details Pass Criteria
RTO Room Temperature Operating
25C/30% RH for 240 hours less than 20% change in L* less than 250% increase in drive current
HHO High Humidity Operating 40ºC and 90% RH for 240 hours less than 20% change in L* less than 250% increase in drive current
HHS High Humidity Storage 60ºC and 80% for 100 hours less than 20% change in L* less than 250% increase in drive current
HTO High Temp Operating 50ºC and 28% for 240 hours less than 20% change in L* less than 250% increase in drive current
HTS High Temp Storage 70C and 23% RH for 240 hours less than 20% change in L* less than 250% increase in drive current
LTS Low Temperature Storage
-25ºC for 240 hours less than 20% change in L* less than 250% increase in drive current
LTO Low Temperature Operating
0ºC for 240 hours less than 20% change in L* less than 250% increase in drive current
TCT Thermal Cycle [-25ºC, 30 mins] to [70ºC, 30 mins] 100 cycles
less than 20% change in L* less than 250% increase in drive current
SUN UV / Solar 768 W/m2 for 7-days[Temp <= 40ºC]
less than 20% change in L* less than 250% increase in drive current
© 2012 Renesas Electronics America Inc. All rights reserved.26
Contact Info
Steve O’NeilE Ink Corporation
SURF Segmented Displays733 Concord Avenue
Cambridge, MA 02148soneil@eink.com+1.617.499.6051
© 2012 Renesas Electronics America Inc. All rights reserved.27
Questions?
© 2012 Renesas Electronics America Inc. All rights reserved.28
Driving the Display
© 2012 Renesas Electronics America Inc. All rights reserved.29
Zones and Digits
A digit is a collective group of segments
Zone is a logical collection of digits or segments or Icons
© 2012 Renesas Electronics America Inc. All rights reserved.30
On board resources
One timer operating at 5 ms Pins configured as output One routine call to EinkDisplayFSM to manage the screen
(usually in the main while loop or using a regular timer interval).
Application
Presentation
Driver
Hardware Abstraction
Physical
© 2012 Renesas Electronics America Inc. All rights reserved.31
Controlling the display using a finite state machine
The EinkDisplayFSM handles every detail about turning the segments black or white.
CurrDisplay array holds the current segments turned ON/OFF. nextDisplay holds the new segments to be turned ON/OFF. A “1” indicates turned ON, “0” indicates OFF.
FSM has four states. START_UPDATE, WAIT, UPDATE_COMPLETE, and IDLE
In order to start an update to the screen, set variable “updateRequest” to TRUE and the FSM switches to WAIT after setting the flag “changingState” as TRUE. It is recommended to not make any changes to the nextDisplay array while this flag is true.
The FSM continues to update the screen while in the WAIT state by making calls to updateScreen.
Once all steps required to update the screen using a particular waveform are done, the FSM switches to UPDATE_COMPLETE and the FSM returns to IDLE.
© 2012 Renesas Electronics America Inc. All rights reserved.32
Defining a Screen using data structures
Screen name Used to identify the structure
Number of display zones Used to identify the number of logical zones on screen
Display Zone information Used to identify the number of segments per digit and number of digits in a
zone Number of pin connections
Used to indicate the number of pins (including dummy segments) used by the display
Pin Connection information Used to identify which pin is connected to which digit segment. (grouped by
zones) Number of Valid ASCII to Segment mappings
Used to indicate the number of valid mapping tables available in memory ASCII to Segment mapping table 01
Pointer to the segment mapping table for ASCII characters ASCII to Segment mapping table 02
Second pointer to the segment mapping table for ASCII characters
© 2012 Renesas Electronics America Inc. All rights reserved.33
Using the “DisplayNumber” API
Provide the DisplayNumber routine with the following: An integer or message to display (8, 16 or 32-bit) A location or zone number Formatting options Information about the screen using the display structure
The DisplayNumber API will set the corresponding pins/segments to be turned ON by indexes in nextDisplay array
Set the updateRequest flag to TRUE. Advantages:
Ease of setting up numbers/ alphabets Uses a look up table indexed by ASCII values to select the segments in a
digit to turn ON Supports 256/128 mappings depending upon the number of pins/segments
per digit Setup is required only once Error checking Easily support multiple screen definitions
© 2012 Renesas Electronics America Inc. All rights reserved.34
Questions?
Renesas Electronics America Inc.© 2012 Renesas Electronics America Inc. All rights reserved.
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